diff --git a/configure b/configure
old mode 100755
new mode 100644
index 66cb312..5b32145
--- a/configure
+++ b/configure
@@ -1020,7 +1020,7 @@ config = {
   'PYTHON': sys.executable,
 }
 
-if options.prefix:
+if options.prefix != None:
   config['PREFIX'] = options.prefix
 
 config = '\n'.join(map('='.join, config.iteritems())) + '\n'
